865 MHz switching-speed step-down DC-DC power converter for envelope tracking

Abstract

Envelope tracking (ET) is an appealing alternative to the widely used Doherty power amplifier (PA) due to its potential to increase efficiency, particularly for high data rate transmissions. In this work, we demonstrate a 28 V, 865 MHz switching speed step-down converter that can be applied to envelope tracking. The converter's ET capability is demonstrated at up to 865 MHz PWM carrier frequency. An integrated RF GaN HEMT and 100 V GaN power switch process is reported, which enables fabrication of a power switch and gate driver on the same IC, necessary for achieving the 865 MHz switching speed. We report a slew rate of the main power switch of 152 V/ns at 50 V, which enables ET with up to 20% less power than that required without ET. To the authors' best knowledge, this is the first demonstration of a GaN MMIC process that integrates a GaN HEMT suitable for X through Ka-band power amplifiers and a high voltage power switch on the same IC.